Method of configuring and transmitting an MMT transport packet

ABSTRACT

The present invention provides a MMT transport packet structure and a method and an apparatus configuring the structure. A method of configuring an MPEG Media Transport (MMT) transport packet for transmitting an MMT payload format, the method comprising: configuring the MMT transport packet so that the MMT transport packet includes at least one MMT payload format unit and a sequence number field for a packet stream, wherein the sequence number field maintains consistency with a sequence number field included in the MMT payload format.

The present application is a Continuation of U.S. application Ser. No.15/069,549, filed on Mar. 14, 2016, which is a Continuation of U.S.application Ser. No. 13/651,059, filed on Oct. 12, 2012, and the presentapplication claims priority to Korean patent application number10-2011-0104858 filed on Oct. 13, 2011 and 10-2012-0113533 filed on Oct.12, 2012, the entire disclosure of which is incorporated by referenceherein, is claimed.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an MPEG Media Transport (MMT) transportpacket and, more particularly, to a method and apparatus for configuringor transmitting an MMT transport packet.

Discussion of the Related Art

A conventional media fragment header is not a part that is processed bya system, but a part that is accessed and processed by a media encoder.If the media fragment header has a complicated structure, there areproblems in that it is difficult to embody the media fragment header andthe availability of the media fragment header is deteriorated.

Korean Patent Registration No. 0965881 (called Cited Invention 1)discloses a system for encoding video data and a system for decodingvideo data. A video data encoding apparatus according to Cited Invention1 includes a first encoding unit for generating a first bit stream byencoding input video data according to a specific syntax; a secondencoding unit for generating a second bit stream by encoding the inputvideo data according to a syntax different from the specific syntax; anda header information generation unit for receiving the first bit streamor the second bit stream and including header information, includingsyntax type information indicating that the first bit stream or thesecond bit stream is a bit stream encoded according to what syntax, inthe first bit stream or the second bit stream. In accordance with CitedInvention 1, video data can be encoded and decoded independently usingdifferent encoding methods and can be subject to scalable encoding andscalable decoding using both the different encoding methods. The citedinvention 1 is problematic in that it includes information on the typeof data stream, information on the type of layer, and information on thetype of scalability, but does not include information on random accessand an Access Unit (AU).

In addition, U.S. Patent No. 2010-0021142 (called Cited Invention 2),entitled “MOVING PICTURE DECODING DEVICE, SEMICONDUCTOR DEVICE, VIDEODEVICE, AND MOVING PICTURE DECODING METHOD” related to an apparatus andmethod for encoding and decoding media, and U.S. Patent Laid-OpenPublication No. 2008-0260041 (called Cited Invention 3), entitled“ADVANCE MACRO-BLOCK ENTROPY CODING FOR ADVANCED VIDEO STANDARD” relatedto an apparatus for encoding video in a video standard, have beendisclosed, but they do not disclose a method of transmitting andreceiving information related to random access and an AU withoutdepending on specific media or a specific codec.

SUMMARY OF THE INVENTION

The present invention provides a MMT transport packet structure and amethod and an apparatus configuring the structure.

In an aspect, a method of configuring an MPEG Media Transport (MMT)transport packet for transmitting an MMT payload format comprisesconfiguring the MMT transport packet so that the MMT transport packetincludes at least one MMT payload format unit and a sequence numberfield for a packet stream, wherein the sequence number field maintainsconsistency with a sequence number field included in the MMT payloadformat.

In another aspect, a method of transmitting an MPEG Media Transport(MMT) transport packet for transmitting an MMT payload format comprisesconfiguring the MMT transport packet so that the MMT transport packetincludes at least one MMT payload format unit and a sequence numberfield for a packet stream and transmitting the configured MMT transportpacket, wherein the sequence number field maintains consistency with asequence number field included in the MMT payload format.

In yet another aspect, a MPEG Media Transport (MMT) transport packetcomprises a header part and at least one Media Fragment Unit (MFU),wherein the MFU comprises at least one MMT payload format unit, theheader part comprises a sequence number field for a packet stream, andthe sequence number field maintains consistency with a sequence numberfield included in the MMT payload format.

An object of the present invention is to provide a new MMT transportpacket structure and a method and apparatus for configuring thestructure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings, which are included to provide a furtherunderstanding of this document and are incorporated on and constitute apart of this specification illustrate embodiments of this document andtogether with the description serve to explain the principles of thisdocument.

FIG. 1 is a conceptual diagram showing an MMT layer structure.

FIG. 2 is a conceptual diagram showing the format of unit information(or data or packet) that is used in each layer of the MMT layerstructure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, some embodiments of the present invention are described indetail with reference to the accompanying drawings in order for thoseskilled in the art to be able to readily implement the invention. It isto be noted the present invention is not limited to the followingembodiments and may be embodied in various forms. Furthermore, parts notrelated to the present invention are omitted in order to clarify thepresent invention in the drawings, and the same or similar referencenumerals are used to denote the same or similar functions throughout thedrawings.

First, the meanings of terms used in this specification are defined asfollows.

A content component or a media component is defined as media of a singletype or a subset of the media of a single type, and it may become, forexample, a video track, movie subtitles, or an enhancement layer ofvideo.

Content is defined as a set of content components, and it may become,for example, a movie or a song.

Presentation is defined as an operation that is performed by one or moredevices so that a user can experience (e.g., watching movies) onecontent component or one service.

Service is defined as one or more content components that aretransmitted for presentation or storage.

Service information is defined as meta data that describes one serviceand the characteristics and components of the service.

An Access Unit (AU) is the smallest data entity, and it may have timeinformation as an attribute.

If an AU is related to coded media data for which time information fordecoding and presentation has not been designated, the AU is notdefined.

An MMT asset is a logical data entity that is formed into at least oneMMT Processing Unit (MPU) along with the same MMT asset ID or formed ofa lump of specific data along with a format defined in another standard.

The MMT asset is the largest data unit to which the same compositioninformation and transport characteristics are applied.

An MMT Asset Delivery Characteristics (MMT-ADC) is a description relatedto QoS requirements for transmitting MMT assets. The MMT-ADC ispresented so that a specific delivery environment cannot be known.

MMT Composition Information (MMT CI) describes a spatial and temporalrelationship between MMT assets.

A Media Fragment Unit (MFU) is a general container and is independentfor any specific codec. The MFU accommodates coded media data which canbe independently consumed by a media decoder. The MFU has a size smallerthan or larger than an Access Unit (AU) and accommodates informationthat may be used in a transport layer.

An MMT package is a set of logically structured data, and it includes atleast one MMT asset, MMT-composition information, and MMT-asset deliverycharacteristics and explanatory information.

An MMT packet is the format of data that is generated or consumed by anMMT protocol.

An MMT payload format is a format for the payload of an MMT package orMMT signaling message that will be transmitted by an MMT protocol or anInternet application layer protocol (e.g., RTP).

An MMT Processing Unit (MPU) is a general container that is independentfor any specific media codec, and it accommodates one or more AUs andinformation related to additional transmission and consumption. Fornon-timed data, an MPU accommodates the part of data that does notbelong to an AU range. An MPU is coded media data that is full and canbe independently processed. In this connection, processing meansencapsulation or packetization as an MMT package for transmission.

Non-timed data defines all data elements which can be consumed withoutspecifying the time. Non-timed data may have a time range in which datacan be executed or started.

Timed data defines a data element that is related to a specific decodedand presented time.

FIG. 1 is a conceptual diagram showing an MMT layer structure.

Referring to FIG. 1, an MMT layer includes an Encapsulation layer(E-layer), a delivery layer, and an S layer. The MMT layer operates overa transport layer.

The E-layer may be responsible for, for example, the packetization,fragmentation, synchronized, and multiplexing functions of transmittedmedia.

An encapsulation functional area defines the logical structures of mediacontent, an MMT package, and the formats of data units to be processedby an entity that complies with MMT. In order to provide informationessential for adaptive transmission, an MMT package specifiescomponents, including media content, and a relationship between thecomponents. The formats of the data units is defined to encapsulatecoded media so that the coded media is stored and transmitted in thepayload of a transport protocol and can be easily converted betweenthem.

The E-layer may include an MMT E.1 layer, an MMT E.2 layer, and an MMTE.3 layer, as shown in FIG. 1.

The MMT E.3 layer generates a Media Processing Unit (MPU) byencapsulating a Media Fragment Unit (MFU) provided by a media codec (A)layer.

Coded media data from a higher layer is encapsulated into an MFU. Thetype and value of coded media may be abstracted so that an MFU can becommonly used in a specific codec technique. In this case, the MFU canbe processed without accessing coded media whose lower layer has beenencapsulated. A lower layer fetches requested coded media data from anetwork or the buffer of a depository and sends the coded media data toa media decoder. AN MFU has a sufficient information media part unit forperforming the above operation.

The MFU may have a format that is independent to a specific codec and onwhich a data unit that can be independently consumed in a media decodermay be loaded. An MFU may become, for example, a picture or slice ofvideo.

A plurality of MFUs which form one or more groups and which can betransmitted and decoded independently generates an MPU. Non-timed mediawhich can be transmitted and decoded independently generates an MPU. TheMPU describes the same internal structure as that of the arrangement andpattern of an MFU that enables rapid access to an MFU and the partialconsumption of the MFU.

The E.2 layer generates an MMT asset by encapsulating the MPU generatedin the E.3 layer.

An MMT asset is a data entity including one MPU or a plurality of MPUsfrom a single data source and is a data unit in which CompositionInformation (CI) and Transport Characteristics (TCs) are defined. TheMMT assess is multiplexed by the MMT payload format and transmitted bythe MMT protocol. The MMT asset may correspond to Packetized ElementaryStreams (PESs) and may correspond to, for example, video, audio, programinformation, an MPEG-U widget, an JPEG image, an MPEG 4 file format, andan MPEG transport stream (M2TS).

The E.1 layer generates an MMT package by encapsulating the MMT assetgenerated in the E.2 layer.

The MMT asset is packaged with MMT-Composition Information (MMT-CI) forthe purpose of a subsequent response of the same user experience alongwith other functional areas (i.e., a transport area and a signal area)or separately from the functional areas. An MMT package is also packagedwith transport characteristics for selecting a proper transmissionmethod for each MMT asset so that the effective quality of the MMT assetis satisfied.

The MMT package may be formed of one MMT asset or a plurality of MMTassets along with pieces of supplementary information, such ascomposition information and transport characteristics. The compositioninformation includes information on a relationship between the MMTassets and may further include information on a relationship between aplurality of MMT packages if a piece of content includes the pluralityof MMT packages. The transport characteristics may include transportcharacteristic information that is necessary to determine a deliverycondition on the MMT asset or the MMT packet and may include, forexample, a traffic description parameter and a QoS descriptor. The MMTpackage may correspond to the program of an MPEG-2 TS.

The delivery layer may perform the network media multiplexing, networkpacketization, and QoS control of media that is transmitted, forexample, over a network.

The delivery function area defines the application layer protocol andformat of a payload. In the present invention, the application layerprotocol provides a characteristic in which the transfer of an MMTpackage is more enhanced than a conventional application layer protocolfor the transmission of multimedia including multiplexing. The payloadformat is defined to transfer coded media data irrespective of the typeof media or an encoding method.

The Delivery layer (D-layer) may include an MMT D.1 layer, an MMT D.2layer, and an MMT D.3 layer, as shown in FIG. 1.

The D.1 layer receives the MMT package generated from the E.1 layer andgenerates an MMT payload format based on the received MMT package. TheMMT payload format is a payload format for transmitting an MMT asset andfor transmitting information on the consumption of an MMT applicationprotocol or the existing application transport protocol, such as an RTP.The MMT payload may include the fragments of an MFU along withinformation, such as an AL-FEC.

The D.2 layer receives the MMT payload format generated in the D.1 layerand generates an MMT packet based on the received MMT payload format. AnMMT transport packet or an MMT packet is a data format that is used inthe application transport protocol for MMT.

The D.3 layer supports QoS by providing a function of exchanging piecesof information between layers through the cross-layer design. Forexample, the D.3 layer can perform QoS control using the QoS parametersof the MAC/PHY layers.

The S layer performs a signaling function. For example, the S layer canperform signaling functions, such as the sessioninitialization/control/management, trick mode based on a server and/or aclient, service discovery, and synchronized of transmitted media.

The signaling functional area defines the formats of messages thatmanage the transfer and consumption of an MMT package. The message forconsumption management is used to transmit the structure of an MMTpackage, and the message for transfer management is used to transmit thestructure of a payload format and the configuration of a protocol.

The S layer may include an MMT S.1 layer and an MMT S.2 layer, as shownin FIG. 1.

The S.1 layer can perform service discovery, the media sessioninitialization/termination of media, the media sessionpresentation/control of media, and an interface function with thedelivery layer (D-layer) and the encapsulation layer (E-layer). The S.1layer may define the formats of control messages between applicationsfor media presentation session management.

The S.2 layer may define the formats of control messages that areexchanged between the delivery end-points of the delivery layer(D-layer) regarding flow control, delivery session management, deliverysession monitoring, error control, and hybrid network synchronizedcontrol.

The S.2 layer may include the establishment and release of a deliverysession in order to support the operation of the delivery layer, themonitoring of a delivery session, flow control, error control, thescheduling of resources for an established delivery session, signalingfor synchronized in a complicated delivery environment, and signalingfor adaptive delivery. The S.2 layer may provide signaling necessarybetween a sender and a receiver. That is, the S.2 layer may providesignaling necessary between a sender and a receiver in order to supportthe above-described operations of the delivery layer. Furthermore, theS.2 layer may be responsible for an interface function with the deliverylayer and the encapsulation layer.

FIG. 2 is a conceptual diagram showing the format of unit information(or data or packet) that is used in each layer of the MMT layerstructure.

A Media Fragment Unit (MFU) 130 may include coded media fragment data132 and a Media Fragment Unit Header (MFUH) 134. The MFU 130 has ageneral container format that is independent to a specific codec and canload the smallest data unit that can be independently consumed in amedia decoder. The MFUH 134 may include supplementary information, suchas media characteristics, for example, loss tolerance. The MFU 130 maybecome, for example, a picture or slice of video.

The Media Fragment Unit (MFU) may define a format that encapsulates thepart of an AU in the transport layer in order to perform adaptivetransmission in a range of the MFU. The MFU may be used to transmit aspecific format of coded media so that the part of the AU can be decodedor discarded independently.

The MFU has an identifier for distinguishing it from other MFUs and mayhave information on a general relationship between MFUs within a singleAU. A dependent relationship between the MFUs in a single AU may bedescribed, and priority related to the MFU may be described as part ofpieces of information. The information may be used to handletransmission in the underlying transport layer. For example, thetransport layer may omit the transmission of MFUs that may be discardedso that QoS transmission in an insufficient bandwidth is supported. Thestructure of the MFU is described later.

An MPU is a set of MFUs including a plurality of the MFUs 130. The MPUmay have a general container format that is independent to a specificcodec and may include media data equivalent to an access unit. The MPUmay have a timed data unit or a non-timed data unit.

The MPU is data that has been processed independently and fully by anentity that complies with MMT. The processing may include encapsulationand packetization. The MPU may include at least one MFU or may includepart of data that has a format defined by another standard.

A single MPU can accommodate an integral number or non-timed data of oneor more Aus. For timed data, an AU may be transferred from at least oneMFU, but one AU cannot be fragmented into a plurality of MPUs. Innon-timed data, one MPU accommodates part of non-timed data that hasbeen processed independently and fully by an entity that complies withMMT.

The MPU is a sequence number and an associated asset ID thatdistinguishes it from other MPUs and can be uniquely identified withinan MMT package.

The MPU may have at least one access point. The first byte of an MPUpayload may always be started from a specific access point. In timeddata, the above fact means that the decoding sequence of the MFU isalways 0 in the MPU payload. In timed data, the presentation durationand decoding sequence of each AU may be transmitted in order to informthe presentation time. The MPU does not have its own initialpresentation time, and the presentation time of the first AU of one MPUmay be described in composition information. The composition informationmay state the first presentation time of the MPU. This is described indetail later.

An MMT asset 150 is a set of MPUs. The MMT asset 150 is a data entityincluding a plurality of MPUs (timed or non-timed) data) from a singledata source. The MMT asset 150 may include asset packaging metadata andsupplementary information, such as a data type. The MMT asset 150 mayinclude, for example, video, audio, program information, an MPEG-Uwidget, a JPEG image, an MPEG 4 File Format (FF), Packetized ElementaryStreams (PESs), and an MPEG transport stream (M2TS).

The MMT asset 150 is a logical data entity that accommodates coded mediadata. The MMT asset 150 may include an MMT asset header and coded mediadata. The coded media data may become a collective reference group ofMPUs having the same MMT asset ID. Data of a type that can beindividually consumed by an entity directly connected to an MMT clientmay be considered as an individual MMT asset. The data type that may beconsidered as an individual MMT asset may include, for example, anMPEG-2 TS, a PES, an MP4 file, an MPEG-U widget package, and a JPEGfile.

The coded media of the MMT asset 150 may be timed data or non-timeddata. The timed data is sight and hearing media data that requires thesynchronized decoding and presentation of specific data on a designatedtime. The non-timed data is data of a data type that can be decoded andprovided on a specific time depending on the supply of service or a userinteraction.

A service provider can generate multimedia service by integrating MMTassets in the state in which the MMT assets are placed on the space-timeaxis.

An MMT package 160 is a set of MMT assets including one or more of theMMT assets 150. The MMT assets within the MMT package 160 may bemultiplexed or concatenated like a chain.

The MMT package 160 is a container format for an MMT asset andconfiguration information. The MMT package provides the depository ofthe MMT asset and the configuration information for MMT program.

An MMT program provider encapsulates coded data into MMT assets anddescribes the MMT assets and the temporal and spatial layout of thetransport characteristics of the MMT assets. The MMT program providergenerates configuration information. An MU and an MMT asset may bedirectly transmitted according to the D.1 payload format. Theconfiguration information may be transmitted through a C.1 presentationsession management message. However, an MMT program provider and aclient which permit the relay of an MMT program or subsequent reusestore the configuration information in an MMT package format.

In parsing an MMT package, an MMT program provider determines whether anMMT asset will be provided to a client through what path (e.g.,broadcast or broadband). Configuration information in an MMT package istransmitted through the C.1 presentation session management messagealong with information related to transmission.

A client receives the C.1 presentation session management message andknows that what MMT program is possible and how the MMT asset for theMMT program is received based on the received C.1 presentation sessionmanagement message.

An MMT package may also be transmitted according to the D.1 payloadformat. The MMT package is packetized and transmitted in the D.1 payloadformat. A client receives a packetized MMT package, configures all orpart of the packetized MMT package, and consumes an MMT program in theconfigured MMT package.

Package information 165 on the MMT package 160 may include configurationinformation. The configuration information may include a list of MMTassets, package identification information, composition information 162and supplementary information, such as transport characteristics 164.The composition information 162 includes information on a relationshipbetween the MMT assets 150.

The composition information 162 may further include information on arelationship between a plurality of MMT packages if a piece of contentincludes the plurality of MMT packages. The composition information 162may include information on a temporal, spatial, and adaptiverelationship within the MMT packages.

Like information that helps the transmission and presentation of an MMTpackage, composition information in MMT provides information on aspatial and temporal relationship between MMT assets within the MMTpackage.

An MMT-CI is a descriptive language that extends HTML5 and providesinformation on the extension. If the HTML5 has been designed so that itdescribes the page-based presentation of content based on text, theMMT-CI basically presents a spatial relationship between sources. Inorder to support presentation that informs a temporal relationshipbetween MMT assets, the MMT-CI may be extended so that it includesinformation related to MMT assets within an MMT package likepresentation resources, time information that determines thetransmission and consumption sequence of the MMT assets, and theadditional attributes of media elements that consume a variety of MMTassets in HTML5.

The transport characteristics information 164 includes information ontransport characteristics and can provide information necessary todetermine a delivery condition on each MMT asset (or an MMT packet). Theinformation on the transport characteristics may include a trafficdescription parameter and a QoS descriptor.

The traffic description parameter may include information on the bitrate of the MFU 130 or the MPU and information on priority. Theinformation on the bit rate may include, for example, information onwhether an MMT asset has a Variable Bit Rate (VBR) or a Constant BitRate (CBR), a bit rate guaranteed for an MFU (or MPU), and a maximum bitrate for an MFU (or MPU). The traffic description parameter may be usedfor resource reservation between a server, a client, and other elementson a delivery path. The traffic description parameter may include, forexample, information on a maximum size of an MFU (or MPU) within an MMTasset. The traffic description parameter may be updated periodically oraperiodically.

The QoS descriptor includes information for QoS control and may include,for example, delay information and loss information. The lossinformation may include, for example, a loss indicator about whether thedelivery loss of an MMT asset has been permitted or not. For example,when the loss indicator is ‘1’, it may indicate ‘lossless’. If the lossindicator is ‘0’, it may indicate ‘loss’. The delay information mayinclude a delay indicator that is used to distinguish sensitivities inthe delivery delay of MMT assets. The delay indicator may indicatewhether the type of MMT asset is conversation, interactive, real time,or non-real-time or not.

A piece of content may include one MMT package or a plurality of MMTpackages.

If a piece of content includes a plurality of MMT packages, compositioninformation or configuration information indicative of a temporal,spatial, and adaptive relationship between the plurality of MMT packagesmay be placed within one of the MMT packages or may be placed outsidethe MMT packages.

For example, in the case of hybrid delivery, some of content componentsmay be transmitted over a broadcast network, and the remaining contentcomponents may be transmitted over a broadband network. For example, inthe case of a plurality of AV streams forming one multi-view service,one stream may be transmitted over a broadcast network, and theremaining streams may be transmitted over a broadband network. The AVstreams may be multiplexed, received individually by a client terminal,and stored therein. Alternatively, there is a scenario in whichapplication software, such as a widget, is transmitted over a broadbandnetwork, and there is a scenario in which AV streams (AV program) istransmitted over a broadcast network.

In the case of the multi-view service scenario and/or the widgetscenario, all AV streams may become one MMT package. In this case, oneof all the AV streams may be stored in only one client terminal, storagecontent becomes part of an MMT package, the client terminal has torecord composition information or configuration information again, andthe recorded content becomes a new MMT package not related to a server.

In the case of the multi-view service scenario and/or the widgetscenario, each of AV streams may become one MMT package. In this case, aplurality of MMT packages forms a piece of content, the MMT packages arerecorded on storage for each MMT package, and there is a need forcomposition information or configuration information indicative of arelationship between MMT packages.

Composition information or configuration information included in one MMTpackage may refer to an MMT asset within another MMT package and maypresent the outside of an MMT package that refers to an MMT package inan out-band situation.

Meanwhile, in order to inform a client terminal of a list of the MMTassets 150 provided by a service provider and a possible path for thedelivery of the MMT package 160, the MMT package 160 is translated intoservice discovery information through a control (C) layer, and an MMTcontrol message may include an information table for service discovery.

A server segments multi-media content into a plurality of segment,allocates pieces of URL information to the plurality of segmentssegmented into a specific number, stores the pieces of URL informationon the respective segments in a media information file, and sends themedia information file to a client.

The media information file may be called a variety of names, such as‘Media Presentation Description (MPD)’ or a ‘manifest file’ depending ona standardization organization for standardizing HTTP streaming. Themedia information file is hereinafter called the MPD.

A Cross-Layer Interface (CLI) is described below.

The CLI is used to exchange pieces of information related to QoS betweenthe application layer and a lower layer including the MAC/PHY layers,and it provides means for supporting QoS to a single entity. The lowerlayer provides information on bottom-up QoS, such as a network channelstate, whereas the application layer provides information on mediacharacteristics as information on top-down QoS.

The CLI provides an integrated interface between a variety of networklayers, including the application layer and IEE802.11 WiFi, IEEE 802.16WiMAX, 3G, and 4G LTE. The common network parameters of a popularnetwork standard are extracted as NAM parameters for the static dynamicQoS control of a real-time media application over various networks. TheNAM parameter may include a Bit Error Rate (BER) value. The BER may bemeasured in the PHY or MAC layer. Furthermore, the NAM value providesthe ID of an underlying network, a possible bit rate, a buffer state, apeak bit rate, a service unit size, and a service data unit loss rate.

Two different methods may be used to provide the NAM value. The firstmethod is to provide an absolute value, and the second method is toprovide a relative value. The second method may be used to update theNAM value during access.

The application layer provides top-down QoS information that is relatedto media characteristics for a lower layer. There are two types ofpieces of top-down information, such as MMT asset level information andpacket level information. The MMT asset information is used for theexchange of capacities in a lower layer and/or for the (re)allocation ofresources. The packet level top-down information is recorded on theproper fields of all packets for a lower layer so that a supported QoSlevel can be identified.

The lower layer provides the application layer with bottom-up QoSinformation. The lower layer provides information on a network statethat varies over time and enables faster and more accurate QoS controlin the application layer. The bottom-up information is presented in anabstracted form in order to support heterogeneous network environments.The parameters are measured in the lower layer and are read from theapplication layer periodically or at the request of an MMT application.

An MMT transport packet is responsible for the application layer fortransmitting an MMT payload format through the transport protocol of anInternet Protocol (IP) network. The structure of an MMT transport packetaccording to the present invention is described below.

For example, in accordance with the present invention, one MMT transportpacket may include one MMT payload format (or an MMT payload formatunit). The aggregation or fragmentation of units according to an MMTTransport Unit (MTU) may be performed by an MMT payload format layer.

For another example, in accordance with the present invention, an MMTtransport packet can accommodate an operation that is commonlyapplicable to the existing Real-time Transport Protocol (RTP) payloadformat.

The MMT payload format may be used as an RTP payload format over the RTPand may be used over the MMT transport packet at the same time. In an IPpacket stream, a sequence number for a packet string, such as errorcheck or recovery, is required. An RTP packet can support a sequencenumber field for the sequence number. Furthermore, if the MMT payloadformat is used over the RTP, the sequence number of the RTP may be used.Furthermore, if the MMT payload format is used over an MMT transportpacket, the MMT transport packet may have a general sequence numberfield for a packet stream in order to maintain consistency with the casewhere the MMT payload format is used over the RTP.

Table 1 below shows an example of an MMT transport packet. Sequence ofelements is not limited to that shown in Table 1, and the elements arenot exclusive. The elements of Table 1 may include other elements or oneor more of the elements shown in Table 1 may be deleted.

TABLE 1 Syntax No. of bits Mnemonic mmt_packet ( ){ 16 sequence_nommt_payload_format ( ) }

In Table 1, sequence_no indicates the sequence number of a packet streamand increase by 1 per packet.

Two types of the greatest functions that are provided for mediastreaming when the RTP is used over a User Datagram Protocol (UDP) layerinclude a packet sequence number and a timestamp. The timestamp providesa Presentation Time Stamp (PTS)-equivalent function. In the MMT, the PTSmay be provided by an E-layer function, more particularly, by an M-unit.

In accordance with the present invention, the packet sequence number isprovided in MMT transmission. A general sequence number system for apacket stream can be supported at the same time when the MMT payloadformat is used over the RTP and the MMT payload format is used over theMMT transport packet.

In the above exemplary systems, although the methods have been describedon the basis of the flowcharts using a series of the steps or blocks,the present invention is not limited to the sequence of the steps, andsome of the steps may be performed in order different from that of theremaining steps or may be performed simultaneously with the remainingsteps. Furthermore, those skilled in the art will understand that thesteps shown in the flowcharts are not exclusive and they may includeother steps or one or more steps of the flowchart may be deleted withoutaffecting the scope of the present invention.

While some exemplary embodiments of the present invention have beendescribed with reference to the accompanying drawings, those skilled inthe art may change and modify the present invention in various wayswithout departing from the essential characteristic of the presentinvention. Accordingly, the disclosed embodiments should not beconstrued to limit the technical spirit of the present invention, butshould be construed to illustrate the technical spirit of the presentinvention. The scope of the technical spirit of the present invention isnot limited by the embodiments, and the scope of the present inventionshould be interpreted based on the following appended claims.Accordingly, the present invention should be construed to cover allmodifications or variations induced from the meaning and scope of theappended claims and their equivalents.

What is claimed is:
 1. An apparatus for generating MPEG Media Transport(MMT) packet structure by packetizing media data, the apparatuscomprising: an encapsulation unit configured generate media processingunit (MPU) by encapsulating at least one media fragment unit (MFU),generate asset including at least one media processing unit and generatean MMT package at least one asset; and a packetization unit configuredto generate the MMT packet structure by packetizing the media processingunit included in the asset, wherein the MPU includes at least one accesspoint indicating information regarding decoding or presentation ofaccess unit, wherein the packetization unit generates the MMT packetincluding a packet sequence number field counting the MMT packettransmitted, and wherein the MMT packet comprises a first MMT packetincluding composition information (CI) including information regardingspatial and temporal relationship between a plurality of assets.
 2. Theapparatus of claim 1, wherein the MMT packet further comprises a secondMMT packet including the media processing unit separate out.
 3. Theapparatus of claim 1, wherein the MMT packet structure operates over atransport layer; and the operations for the MMT packet furthercomprising: an MPU Encapsulation, for performing packetization,fragmentation, and synchronization functions of transmitted media; aDelivery of MMT package, for performing management of transport flows,media multiplexing, error control, the scheduling for an deliverysession, signaling for synchronization in a delivery environment; and amessage Signaling, for signaling message for defining formats of messagethat manage a transfer and consumption of an MMT package, apresentation, control and management of the transmitted media, andsynchronization of the transmitted media.
 4. The apparatus of claim 1,wherein the asset comprises at least one MPU sharing the same MMT assetID, and wherein the MPU is identified by the MMT asset ID and a MPUsequence number.
 5. The apparatus of claim 1, wherein a value of thepacket sequence number field is increased by 1 per the MMT packettransmitted.
 6. The apparatus of claim 1, wherein the compositioninformation includes temporal and spatial information regardingrelationship between the plurality of assets.
 7. A method for generatingMPEG Media Transport (MMT) packet structure by packetizing media data,the method comprising: generating media processing unit (MPU) byencapsulating at least one media fragment unit (MFU), generate assetincluding at least one media processing unit and generate an MMT packageat least one asset; and generating the MMT packet structure bypacketizing the media processing unit included in the asset, wherein theMPU includes at least one access point indicating information regardingdecoding or presentation of access unit, wherein the packetization unitgenerates the MMT packet including a packet sequence number fieldcounting the MMT packet transmitted, and wherein the MMT packetcomprises a first MMT packet including composition information (CI)including information regarding spatial and temporal relationshipbetween a plurality of assets.
 8. The method of claim 7, wherein the MMTpacket further comprises a second MMT packet including the mediaprocessing unit separate out.
 9. The method of claim 7, wherein the MMTpacket structure operates over a transport layer; and the operations forthe MMT packet further comprising: an MPU Encapsulation, for performingpacketization, fragmentation, and synchronization functions oftransmitted media; a Delivery of MMT package, for performing managementof transport flows, media multiplexing, error control, the schedulingfor an delivery session, signaling for synchronization in a deliveryenvironment; and a message signaling, for signaling message for definingformats of message that manage a transfer and consumption of an MMTpackage, a presentation, control and management of the transmittedmedia, and synchronization of the transmitted media.
 10. The method ofclaim 7, wherein the asset comprises at least one MPU sharing the sameMMT asset ID, and wherein the MPU is identified by the MMT asset ID anda MPU sequence number.
 11. The method of claim 7, wherein a value of thepacket sequence number field is increased by 1 per the MMT packettransmitted.